U.S. Pat. No. 3,944,151 discloses an apparatus for automatically splicing an expiring web onto a new web roll by successively firing a bumper roll and a knife roll, respectively, to perform either an oversplice or an undersplice. The bumper roll serves to bring the expiring web in contact with the new web roll while the knife roll then severs the trailing edge of the old web.
U.S. Pat. No. 4,530,265 discloses a rotary cutoff knife assembly wherein a support is mounted on a frame for rotary motion around a first axis, and a knife blade is mounted on the support for rotary motion around a second axis parallel to and spaced from the first axis. Means are provided for concomitantly driving the support: and the blade around the axes such that the blade moves from a first position remote from the web to a second position at which it engages and severs the web and then back to the first position.